M3 Barrel question

[Bondster]

I just purchased an M3 online and it has the 18" barrel with the rifle sights on the barrel. I want Ghost ring sights and was wondering if the M3 uses the same barrel as the M1 and M2. If so, it seems it would be easier to just change barrels and have the rear sight installed.

[JakeisaHassell]

I just bought an m3 with ghost rings. I'll trade you. 

[bambihunter]

No, not at all. Remember the M3 has the pump action so it has a different cutouts to allow that action. Also, if you are looking, make sure you get the right age/generation of M3 barrel. From what I can tell, the older HK era models look different than the newer M3's. If it follows the other models like M1 to M2 changes, it will have a barrel ring to give a positive stop when inserting the barrel to the receiver. The older M1's as well as M3's did not have that. It's been a long time since I had either of my M3T folders apart, but the barrel lug behind the ring was shorter on the older SBE's, M1's, etc. than the newer models. The M3 has the indent where the slide lock catches so that may or may not hold true on the M3, but they are certainly different than any other Benelli barrel. 
Also, you didn't mention yours being a folder, but if it is, they took a unique barrel to function completely as the rear sight location is slightly different and use completely different sights. If you put a non-folder barrel on a folding stock model, the sight doesn't lock the folded stock in place like shown in the top picture. Those sights is how it locks, and there's a release button on them to allow the user to fold it down. 

If you have the newer style M3, you can likely buy a new one at places like Numrich, Midway, etc. Be prepared however as most Benelli semi-auto barrels are ~$500 and up for new ones. Good luck on your quest.

The M3's are fairly unique in the shotgun world. There may be others, but the only others that I know of that are both semi-auto and pump like the M3 is the detachable magazine Franchi SPAS-15 and tube magazine SPAS-12 which looks cool but is a pain to use. Its controls are just awkward. 

I just saw the original post was 16 years ago and was necro-bumped. LOL

Edited April 17 by bambihunter